The present invention relates to the packaging of dry powders and particularly to the metering and packaging of precise quantities of pharmaceuticals and drugs for medical uses. The invention has particular utility in the metering and packaging of dry powders, particularly very small amounts of dry powder pharmaceuticals and drugs, and will be described in connection with such utility, although other utilities are contemplated.
The certification of new pharmaceuticals is a lengthy and costly process involving animal studies followed by chemical trails to establish both efficacy and safety. Because a pharmaceutical's characteristics may be affected by changes in manufacturing and/or packaging, the approval process limits the approval to a particular manufacturing and packaging process.
In our earlier U.S. Pat. No. 5,699,649, granted Dec. 23, 1997, we describe a method and apparatus for packaging microgram quantities of fine powders such as pharmaceuticals using electrostatic phototechnology techniques. More particularly, as described in our aforesaid U.S. Pat. No. 5,699,649, the ability of powders to acquire an electrical charge advantageously is utilized for precisely measuring exact microgram quantities of the powder, whereupon these exact microgram quantities are then placed in individual containers, and the containers sealed.
Electrostatic charge has been employed to attract a given quantity of powder to a surface. An example of this is the laser printer or the electrostatic copy devices where a drum is charged and toner particles are attracted and held in position by the charge. The charge on the drum is neutralized by the attracted toner powder, thus limiting the amount of toner in accordance with the charge image on the drum. The charge on these printer drums is then transferred to a sheet of paper or other carrier to give a final image. In our U.S. Pat. No. 5,699,649, the same electrostatic charge technology is employed for transferring a predetermined amount of a finely powdered pharmaceutical or drug to a carrier or an intermediate such as a drum, carrying a charge of predetermined intensity and area, rotating the charged drum surface, carrying the predetermined amount of powdered pharmaceutical or drug on its surface, to a transfer station where the charge is overcome and the dry powder is transferred to a package which is then sealed. In lieu of a drum, a belt, or other movable surface is charged to a given potential in a localized area.
When a given amount of a powdered pharmaceutical or drug is to be packaged, the charge and area of charge can be determined experimentally for each dose of pharmaceutical or drug and each particle size distribution. This can be done by controlling either the charged area for a given charge density or the total electrostatic charge on any individual charged area. These conditions can be adjusted to provide essentially the exact desired amount of the particular pharmaceutical or drug to be transferred at the transfer station.